Regarding the location of base stations in a communications network, many security or commercial applications rely on the precise knowledge of the locations of base stations in a communications network. Generally, network operators are involved with the set up of these commercial applications, and the locations of the base stations are known in advance. There may be cases, however, where the network operators are not cooperative. There may also be cases, e.g., for security applications, where these applications are used without the knowledge of the network operators. There is also a need in the art for automatically adding the location of a base station and associated information with the base station to a database when a new base station is installed in a network. For example, co-pending U.S. patent application Ser. No. 12/104,250, filed Apr. 16, 2008, entitled “System and Method for Locating UMTS User Equipment Using Measurement Reports,” the entirety of which is incorporated herein by reference, discusses determining the location of user equipment (“UE”) assuming that the locations of base stations in a measurement report are known. If such is not the case, then the methods described in embodiments of the present subject matter may be utilized to determine the locations of unknown or newly installed base stations or Node Bs, and then the location of a UE determined.
It is known that any electromagnetic wave emitting object may be located by utilizing sensors that receive the waves combined with an a geolocation process such as triangulation, multilateration, AOA, etc. In several networks, operators have installed location measurement units (“LMUs”) therein which may be utilized as sensors for these processes. If multilateration (i.e., TDOA positioning) is utilized then at least four LMUs are generally required resulting in three independent hyperbolas. The intersection point of these three hyperbolas may be the estimated location of the unknown base station or Node B. In some cases, however, these hyperbolas may not intersect exactly at one point, and a more accurate location may be determined based on the LMU geometry, received signal quality, etc.
Embodiments of the present subject matter therefore provide a novel method and system to derive OTDOA information from the existing mobile devices and base stations utilizing messages typically used for normal operation of the mobile device. For example, measurement report messages, e.g., network measurement reports, are generally utilized for managing handover. UMTS mobile devices report these messages to a base station for proper operation. These messages contain the Connection Frame Number (“CFN”)—System Frame Number (“SFN”) information between serving and neighbor nodes, such as, but not limited to, base stations, base station sectors, cells, etc. Embodiments of the present subject matter may also derive a neighboring node's SFN-SFN OTD from this information. Moreover, if the neighboring SFN times are known, OTDOAs of the neighboring node downlink may be determined. Embodiments of the present subject matter may therefore make it possible to determine downlink OTDOA values for mobile devices that do not support the OTDOA feature through the exploitation of network measurement reports that are generally not intended for location determination.
Accordingly, there is a need for a method and system for locating an unknown base station or Node B using measurement reports and for generating location determining hyperbolas by combining a UE measurement report with LMU measurements. Therefore, an embodiment of the present subject matter provides a method for estimating a location of an unknown Node B in a wireless communications system having a plurality of known nodes. The method may comprise determining an OTDOA hyperbola based on signals received from the unknown Node B and one of the known nodes. The OTDOA hyperbola may be determined using information received from a user equipment network measurement report, the user equipment being at any known location.
Another embodiment of the present subject matter may provide a method for estimating a location of an unknown Node B in a wireless communication system having a plurality of other nodes and a plurality of LMUs. The method may comprise determining first and second values based on a network timing characteristic for ones of the nodes. An OTDOA hyperbola may be calculated based on the first and second values, and a location of the unknown Node B determined as a function of the OTDOA hyperbola.
A further embodiment of the present subject matter may provide another method for estimating a location of an unknown Node B in a wireless communication system having a plurality of other nodes and a plurality of LMUs. The method may comprise determining a first value based on a network measurement report characteristic, a second value based on a first network timing characteristic, a third value based on a second network timing characteristic, and a fourth value based on a third network timing characteristic. An OTDOA hyperbola may be calculated based on at least one of the first, second, third, or fourth values, and a location of the unknown Node B estimated as a function of the OTDOA hyperbola.
An additional embodiment of the present subject may provide a further method for estimating a location of an unknown Node B in a wireless communication system having a plurality of other nodes and a plurality of LMUs. The method may comprise determining a first value based on a first network measurement report characteristic, a second value based on a second network measurement report characteristic, a third value based on a first network timing characteristic, and a fourth value based on a second network timing characteristic. An OTDOA hyperbola may be calculated based on at least one of the first, second, third, or fourth values, and a location of the unknown Node B estimated as a function of the OTDOA hyperbola.
Another embodiment of the present subject matter may provide an additional method for estimating a location of an unknown Node B in a wireless communication system having a plurality of other nodes and a plurality of LMUs. The method may comprise determining a first value based on a first network measurement report characteristic, a second value based on a second network measurement report characteristic, a third value based on a third network measurement report characteristic, and a fourth value based on a network timing characteristic. An OTDOA hyperbola may be calculated based on at least one of the first, second, third, or fourth values, a location of the unknown Node B estimated as a function of the OTDOA hyperbola.
One embodiment of the present subject matter may provide a system for estimating a location of an unknown Node B in a wireless communication system having a plurality of other nodes and a plurality of LMUs. The system may comprise circuitry for determining a first value based on a network timing characteristic for one of the nodes and circuitry for determining a second value based on a network measurement report characteristic. The system may also include circuitry for calculating an OTDOA hyperbola based on the first and second values and circuitry for estimating a location of said unknown Node B as a function of said OTDOA hyperbola.
Another embodiment of the present subject matter provides a method for estimating a location of an unknown Node B in a wireless communication system having a plurality of other nodes and a plurality of LMUs. The method may include determining a first value based on a first network timing characteristic of the unknown Node B at a first LMU and determining a second value based on a second network timing characteristic of the unknown Node B at a second LMU. One or more OTDOA hyperbolas may be calculated based on at least the first and second values. A third value based may be determined on a third network timing characteristic of a known Node B at one of said first or second LMUs. A first timing offset value between the known and unknown Node Bs may be determined as a function of any one or combination of the first, second and third values, and a second timing offset value between the known and unknown Node Bs determined using a UE network measurement report. A propagation delay from the known Node B to the LMU or UE may be determined as a function of the timing offset values, and one or more OTDOA hyperbolas calculated based on ones of the first timing offset value, second timing offset value, third value, and propagation delay. A location of the unknown Node B may then be estimated as a function of said OTDOA hyperbolas.
These embodiments and many other objects and advantages thereof will be readily apparent to one skilled in the art to which the invention pertains from a perusal of the claims, the appended drawings, and the following detailed description of the embodiments.